Depression is an affectivity disorder in which a depressive syndrome is conspicuous, “depressive” being understood to refer to a state of dejection or melancholia. The antidepressants used for therapy are also important adjuvants for pain therapy (Tzschentke, N A and 5-HT Reuptake inhibitor and α2 agonist, in Analgesics: From Chemistry and Pharmacology to Clinical Application, Pages 265 to 284, Wiley 2002), particularly with chronic states of pain, since the constant pain can lead to a depressive mood in the patients. This is very frequently the case with cancer patients suffering pain (Berard, INT. MED—J. 1996, 3/4, 257-259). Since no analgesics are as yet known which contain a clinically relevant active antidepressant component, the antidepressants must be added as supplementary medication over and above the administration of analgesic. Since patients chronically in pain frequently require a large number of various pharmaceutical preparations, an additional dose of antidepressant will lead to a further strain on the organism. For this reason and also to improve the compliance, there is a high demand for a pharmacological active substance that preferably also has an active antidepressant component in addition to its analgesic action. The basis for such an antidepressant action in a pharmacological active substance is its capability to inhibit the reuptake of serotonin.